22 



GEOLOGY OF THE ISLE OF WIGHT. 



In every case where the junction was exposed, the same 

 brecciated appearance in the surface of the Wealden Beds was 

 observable, sometimes extending to a depth of 2 feet into the 

 Wealden. There can be little doubt that it indicates that a 

 certain amount of erosion of these beds took place before the 

 Lower Greensnnd was deposited. In addition to the particles of 

 quartz which give to the Perna Bed its gritty character, there 

 are in it small rolled phosphatic nodules. 



The Atherfield Clay, excepting the top beds, can be seen only 

 as a flowing mass of pale-blue clay, with phosphatic concretions. 

 Its thickness consequently is difficult to determine, but so far as 

 can be judged it is like the other beds considerably thinner than 

 at Atherfield, and may be estimated at about 60 feet. 



The succeeding beds are clearly exposed, and are shown in 

 descending order in the following detailed section : — 



Compton Bay. 



Vt. In. 



Carstone, 

 Gft. 



Sand-rock 

 Series, 

 81 ft. 6 ins. 



S 





10 



56 



Brown sand, with .'j-inch pebble-band at the base, 

 containing rounded quartzite pebbles up to 

 f inch in diameter, some phosphatic pebbles, and 

 many pieces of wood. Cylindrical ])hosphatic 

 nodules also occur - - - -CO 



fBkieclay- - - - - - 2 6 



Pebble-band with quartzites, &c., 0-3 inch -H 



Grey and greenish sand, with a layer of pyritised 



wood 82 feet from the top, and scattered frag- ^13 

 ments near the top, about 12^ feet - - | 



Pebble-band, as above, 6 inches - - -J 



Bright-yellow sand, with an irony seam at the 

 base --.... 



Clean white sand and blue clay, interbedded in 



wavy laminae, and giving out copious chaly- 



beate springs (" foliated series ") 



"Clayey grit, weathering green, with a band of 



quartzite pebbles, 5 inches thick, at the base - 



White sand like gannister ... 



Dark sand and clay intermixed, with much vege- 

 table matter in the upper part, and looking 

 like a rootlet-bed* - . . _ 



Band of small quartzite pebbles . . - 



Sand like gannister . - . . 



Very black and sooty-looking sand or silt 



Lighter do. striped 



Band of soft yellow rolled phosphatic nodules, 

 with some quartzites . - . - 



Lighter coloured and striped " sooty " sand, with 

 many small soft yellow phosphate pebbles near 

 the base ..... 



" Foliated " sand and clay as above, passing 

 down into paper-shale . - - - 



f Very green gritty sand, with hard pale-yellow 

 phosphates, some cylindrical, some rounded 



Brown sandstone .... 



251 ft. 64 ins. | Green grit as above .... 



Ferruginous 

 Sands 



u 



4 



5 8 



< 



* This and the other dark sands were tested by Mr. C. Tookej- for manganese, 

 but found to contain none. The colouring matter ai)peared to be carbonaceous. 



f This !ind Ithc seven hods followiiiir it crop out in the west side of Compton 

 Chine. Jts grceu colour is due to an abundance of grains of glauconite. See p. 255 

 i'or an analysis of a specimen from this bed. 



